Method of connecting a filament to a support in an electric filament lamp

ABSTRACT

A filament lamp in which the connection of the filament to the support is effected by means of a flattened sleeve in which the end of the filament is incorporated and against the outer wall of which a support is welded, preferably spot welded.

United States Patent [191 Pastijn et a1.

1 1 Dec. 17, 1974 METHOD 0F CONNECTING A FILAMENT TO A SUPPORT IN AN ELECTRIC FlLAMENT LAMP [75] Inventors: Leopold Stanislas Maria Pastijn,

Deurne; Ghislain Felix Alfons Arthur Verboven, Genk, both of Belgium [73] Assignee: U.S. Philips Corporation, New

York, NY.

[22] Filed: Sept. 12, 1973 [21] Appl. No.: 396,449

Related U.S. Application Data [62] Division of Ser. No. 218,269, Jan. 17, 1972,

abandoned [30] Foreign Application Priority Data Jan. 16, 1971 Netherlands 7100606 [52] U.S. Cl. 29/25.l5, 313/271 [51] Int. Cl. HOlj 9/00 [58] Field of Search 29/25.13, 25.14, 25.15,

[56] References Cited UNITED STATES PATENTS 1,431,158 10/1922 Heany 313/333 X 2,247,688 7/1941 Kinyon 313/333 X 2,716,714 8/1955 Adams et a1... 313/271 3,243,633 3/1966 Ackerman 313/271 FOREIGN PATENTS OR APPLICATIONS 948,720 9/1956 Germany Primary ExaminerRoy Lake I Assistant Examiner-James W. Davie Attorney, Agent, or Firm-F. R. Trifari 57 ABSTRACT I A filament lamp in which the connection of the fila ment to the support is effected by means of a flattened sleeve in which the end of the filament is incorporated and against the outer wall of which a support is welded, preferably spot welded.

1 Claim, 3 Drawing Figures METHOD OF CONNECTING A FILAMENT TO A SUPPORT IN AN ELECTRIC FILAMENT LAMP This is a division, of application Ser. No. 218,269, filed Jan. 17, 1972 now abandoned.

The invention relates to an electric filament lamp which comprises a lamp envelope in which a filament is incorporated, the filament being secured with each of its ends in a metal sleeve against the outer wall of which a support is welded, said support being secured in the lamp envelope. Such a filament lamp is known, inter alia, from German Pat. No. 948,720. In the filament lamp described in this specification, the sleeve is formed as an elongate circular pipe of molybdenum which comprises a coaxially extending slot, which pipe encloses the end of the filament member in a clamping manner. The support is secured against the outer wall of the pipe by electric arc welding.

This known construction has the following drawbacks: the pipe should be comparatively long in order that the end of the wire is rigidly clamped. The provision of the end of the wire in the pipe is not simple because the inside diameter of the pipe in the unloaded condition is smaller than the diameter of the end of the wire. Furthermore, the electric arc welding of components having such small dimensions is a timeconsuming precision job.

The invention is based on the recognition of the fact that a lamp construction can be obtained which does not exhibit these drawbacks at all when the sleeve in the welded condition does not have a circular but a non-circular cross section.

The electric filamentlamp according to the invention is therefore characterized in that the sleeve has a non-circular cross section over at least a part of its length and is welded against the support at the area of said part with its largest transverse dimension.

' A favourable embodiment of the electric filament lamp according to the invention is characterized in that the sleeve is formed by flattening from a sleeve the average inner diameter of which is from 1.5 to 3'times as large as the diameter of the end of the filament.

By flattening the sleeve which, originally, was for example, a circular sleeve in whichthe end of the filament is inserted, the said endis clamped. As a result of this, a good connection can be obtained all the same with a comparatively short sleeve. Because the average inner diameter of the sleeve is larger than the diameter of the end of the filament, inserting said end into the sleeve presents fewer problems than in the known filament lamp. It has been found that a connection which has a good tensile strength can be realized when the average inner diameter of the sleeve is from 1.5 to 3 times as large as the diameter of the'end of the filament.

A favourable embodiment of the electric filament lamp according to the invention is characterized in that the connection of each end of the filament in the sleeve and of the support against the outer wall of the sleeve is carried out by means of at least one single spot weld.

The advantage of this embodiment is that a connection can be obtained with measures which are very simple to realize, which connection has proved to be of a very high quality. This is done as follows: the sleeve is slipped over the end of the filament and the support is moved in the desirable position against the cylinder wall of the sleeve after which the connection of the end to the sleeve and of the sleeve to the support is produced by means of a spot weld. The sleeve is flattened between the electrodes of the welding apparatus in such manner that the end is clamped in the sleeve and welded with a sufficient current strength.

Both a seamless sleeve and a sleeve having a slot extending parallel to the axis may be used if the wall thickness of the sleeve is suitably chosen.

In order that the invention may be readily carried into effect, one embodiment thereof will now be described in greater detail, by way of example, with reference to the accompanying drawing, in which:

FIG. 1 is a perspective view of the connection,

FIGS. 2 and 3 each show a phase during the manufacture.

As shown in FIG. 1, the helically wound filament 1 ends in a straight wire end 2 which is incorporated in a sleeve 3. The sleeve 3 is secured to the support 4 in the form of a pole wire by means of a spot weld.

FIGS. 2 and 3 show how the originally circular sleeve 6 with the wire 7 incorporated is moved in a position against the pole wire 8 between the electrodes 9, 10 of a welding apparatus. By moving the electrodes towards each other, the sleeve 6 is flattened (FIG. 3), as a result of which a good connection is realized between the pole wire 8 and the sleeve 6 as well as between the wire end 7 and the sleeve 6.

ln this embodiment the inner diameter of the sleeve prior to mounting was 250 microns and the outer diameter was 450 microns, while the wire diameter was 167 microns. In this embodiment the sleeve and the pole wire were manufactured from molybdenum and the filament from tungsten.

Besides as a pole wire, the support may of course also be shaped as a screening cap incorporated in the lamp, which screening cap is used in car lamps.

What is claimed is:

I. A method of connecting a filament to a support in an electric filament lamp comprising the steps of:

inserting an end of the filament in a cylindrical sleeve;

' juxtaposing the sleeve containing said filament end transversely to and in contact with said support; and

simultaneously compressing said sleeve against said filament wire and support to deform said sleeve into a non-circular cross section and spot welding said compressed sleeve to said support and said filament to said sleeve. 

1. A method of connecting a filament to a support in an electric filament lamp comprising the steps of: inserting an end of the filament in a cylindrical sleeve; juxtaposing the sleeve containing said filament end transversely to and in contact with said support; and simultaneously compressing said sleeve against said filament wire and support to deform said sleeve into a non-circular cross section and spot welding said compressed sleeve to said support and said filament to said sleeve. 